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SUMMARY:EESS talk on "Ecosystem metabolism and carbon fluxes in a sub-alpi
 ne stream network"
DTSTART:20170321T121500
DTEND:20170321T131500
DTSTAMP:20260427T231049Z
UID:b41e57c57bbe5727e5dcef4eea74fc3675da7153e3d68901e8a24a9d
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr Amber Ulseth\, SBER\nShort biography:\nAmber J. Ulseth is c
 urrently a Scientist within the Stream Biofilm and Ecosystem Research (SBE
 R) laboratory at EPFL. Her research has included studying the incorporatio
 n of anthropogenic nitrogen and carbon into urban stream food webs\, the r
 ole of migratory fish on nitrogen cycling in Venezuelan streams\, and diss
 olved organic carbon cycling in the Colorado River Basin\, USA. Amber is c
 urrently working on ecosystem metabolism and carbon fluxes in streams of t
 he Austrian and Swiss Alps. Prior to working at EPFL\, Amber was a post-do
 ctoral researcher with Prof. Dr. Tom Battin at the University of Vienna. A
 mber received her BS from the University of Minnesota-Duluth\, her MS from
  the University of North Carolina Greensboro\, and her PhD from the Univer
 sity of Wyoming.\nAbstract:\nStream metabolism describes the amount of car
 bon produced and turned over at the ecosystem level. Both ecosystem respir
 ation (ER) and gross primary production (GPP) are driven by a number of co
 ntrolling variables\, including water temperature and hydrology. Using con
 tinuous measurements of ecosystem metabolism\, I will discuss the patterns
  and processes of ecosystem metabolism across the Ybbs River Network (YRN)
 \, a sub-alpine stream network located in the Austrian Alps. Temperature c
 an drive metabolism\, which was quantified as described by Arrhenius kinet
 ics. Network-wide ER activation energy (AE) was 0.60 electron volts (eV)\,
  which was within the expected range for metabolism kinetics. However\, ne
 twork-wide AE for GPP was 1.8 to 2.4-fold greater (0.67 eV) than predicted
  based on metabolism kinetics alone. The variability in AE of ER and GPP w
 ithin the network indicates that individual streams may respond differentl
 y to changing environmental conditions\, such as changes in the timing and
  delivery of snowmelt. The winter of 2013/2014 was anomalously warm compar
 ed to the previous winter across the study catchment\, resulting in a shif
 t of winter precipitation from snow to rain. My findings when comparing ec
 osystem metabolism across the years\, suggest that the YRN evolved from a 
 transient sink to source of carbon dioxide (CO2) in spring as snowmelt hyd
 rology differed following the high snow versus low snow winter.  This shi
 ft towards increased heterotrophy during spring snowmelt following a warm 
 winter has potential consequences towards annual ecosystem metabolism\, as
  spring GPP contributed on average 33% to annual GPP fluxes compared to sp
 ring ER\, which averaged 21% of annual ER fluxes. We propose that Alpine h
 eadwaters shunt less organic carbon to downstream ecosystems\, but will em
 it more within-stream respiratory CO2 to the atmosphere annually\, as the 
 climate gets warmer.\n 
LOCATION:GR C0 01 https://plan.epfl.ch/theme/generalite_thm_v2?room=GR%20C
 0%2001&dim_floor=0&lang=en&dim_lang=en&tree_groups=centres_nevralgiques%2C
 acces%2Cmobilite_reduite%2Censeignement%2Ccommerces_et_services%2Cvehi
STATUS:CONFIRMED
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